Comparative study of various PV technologies in terms of energy yield and annual degradation

Current accelerated tests of photovoltaic (PV) modules mostly prevent infant mortality but do not fully duplicate changes occurring in the field nor can predict useful lifetime. Therefore, monitoring of field-deployed thin film PV modules was undertaken at FSEC with goals to assess their performance in hot and humid climate under high voltage operation and to correlate the PV performance with the meteorological parameters. This paper presents performance analysis of a-Si:H and CIGS PV modules that were field deployed in the hot and humid climate over a period of approximately 30 months. The modules were connected in series so as to build maximum open circuit voltage of less than ±600 V with respect to ground and maintained at near maximum power point conditions. Statistical data analysis of PV parameters along with meteorological parameters that were continuously monitored is carried out on regular basis with PVUSA type regression analysis. Current-voltage (I-V) characteristic of module arrays that are obtained periodically complement the continuous data monitoring. The annual energy yield was calculated for both the PV technologies based on the data averaged over every fifteen minutes. Moreover, comparison of the two technologies was carried out based on the estimated annual degradation.